Density-functional theory (DFT) is a quantum-mechanical theory that
allows the properties of materials to be calculated from first
principles or ab initio i.e. without making any prior
assumptions about how the system under study should behave. This
means it can even predict the properties of
materials that have not yet been made. DFT
is popular because it is sufficiently accurate for many
purposes at a computational cost that is relatively cheap.
The computational cost of conventional DFT calculations scales as the cube of the system-size, limiting traditional methods to a few hundred atoms. My research focuses on the development of linear-scaling methods, their implementation within the ONETEP code and their application to the study of nanoparticles and biological systems in particular. A distinctive feature of the ONETEP method is the optimization of local orbitals (as shown in a barium titanate crystal above) in a manner equivalent to the plane-wave pseudopotential method used in the most popular conventional DFT methods.